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Xu JH, He TH, Wang NP, Gao WM, Cheng YJ, Ji QF, Wu SH, Wei YL, Tang Y, Yang WZ, Zhang J. Thermoregulatory pathway underlying the pyrogenic effects of prostaglandin E 2 in the lateral parabrachial nucleus of male rats. Acta Pharmacol Sin 2024; 45:1832-1847. [PMID: 38702500 PMCID: PMC11336216 DOI: 10.1038/s41401-024-01289-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2023] [Accepted: 04/10/2024] [Indexed: 05/06/2024] Open
Abstract
It has been shown that prostaglandin (PG) E2 synthesized in the lateral parabrachial nucleus (LPBN) is involved in lipopolysaccharide-induced fever. But the neural mechanisms of how intra-LPBN PGE2 induces fever remain unclear. In this study, we investigated whether the LPBN-preoptic area (POA) pathway, the thermoafferent pathway for feed-forward thermoregulatory responses, mediates fever induced by intra-LPBN PGE2 in male rats. The core temperature (Tcore) was monitored using a temperature radiotelemetry transponder implanted in rat abdomen. We showed that microinjection of PGE2 (0.28 nmol) into the LPBN significantly enhanced the density of c-Fos-positive neurons in the median preoptic area (MnPO). The chemical lesioning of MnPO with ibotenate or selective genetic lesioning or inhibition of the LPBN-MnPO pathway significantly attenuated fever induced by intra-LPBN injection of PGE2. We demonstrated that EP3 receptor was a pivotal receptor for PGE2-induced fever, since microinjection of EP3 receptor agonist sulprostone (0.2 nmol) or EP3 receptor antagonist L-798106 (2 nmol) into the LPBN mimicked or weakened the pyrogenic action of LPBN PGE2, respectively, but this was not the case for EP4 and EP1 receptors. Whole-cell recording from acute LPBN slices revealed that the majority of MnPO-projecting neurons originating from the external lateral (el) and dorsal (d) LPBN were excited and inhibited, respectively, by PGE2 perfusion, initiating heat-gain and heat-loss mechanisms. The amplitude but not the frequency of spontaneous and miniature glutamatergic excitatory postsynaptic currents (sEPSCs and mEPSCs) in MnPO-projecting LPBel neurons increased after perfusion with PGE2; whereas the frequency and amplitude of spontaneous inhibitory postsynaptic currents (sIPSCs) and the A-type potassium (IA) current density did not change. In MnPO-projecting LPBd neurons, neither sEPSCs nor sIPSCs responded to PGE2; however, the IA current density was significantly increased by PGE2 perfusion. These electrophysiological responses and the thermoeffector reactions to intra-LPBN PGE2 injection, including increased brown adipose tissue thermogenesis, shivering, and decreased heat dissipation, were all abolished by L-798106, and mimicked by sulprostone. These results suggest that the pyrogenic effects of intra-LPBN PGE2 are mediated by both the inhibition of the LPBd-POA pathway through the EP3 receptor-mediated activation of IA currents and the activation of the LPBel-POA pathway through the selective enhancement of glutamatergic synaptic transmission via EP3 receptors.
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Affiliation(s)
- Jian-Hui Xu
- Key Laboratory of Thermoregulation and Inflammation of Sichuan Higher Education Institutes, Chengdu Medical College, Chengdu, 610500, China
| | - Tian-Hui He
- Key Laboratory of Thermoregulation and Inflammation of Sichuan Higher Education Institutes, Chengdu Medical College, Chengdu, 610500, China
| | - Nan-Ping Wang
- Key Laboratory of Thermoregulation and Inflammation of Sichuan Higher Education Institutes, Chengdu Medical College, Chengdu, 610500, China
| | - Wen-Min Gao
- Key Laboratory of Thermoregulation and Inflammation of Sichuan Higher Education Institutes, Chengdu Medical College, Chengdu, 610500, China
| | - Yong-Jing Cheng
- Key Laboratory of Thermoregulation and Inflammation of Sichuan Higher Education Institutes, Chengdu Medical College, Chengdu, 610500, China
| | - Qiao-Feng Ji
- Key Laboratory of Thermoregulation and Inflammation of Sichuan Higher Education Institutes, Chengdu Medical College, Chengdu, 610500, China
| | - Si-Hao Wu
- School of Clinical Medicine, Chengdu Medical College, Chengdu, 610500, China
| | - Yan-Lin Wei
- School of Clinical Medicine, Chengdu Medical College, Chengdu, 610500, China
| | - Yu Tang
- Key Laboratory of Thermoregulation and Inflammation of Sichuan Higher Education Institutes, Chengdu Medical College, Chengdu, 610500, China
| | - Wen Z Yang
- School of Life Science and Technology, Shanghai Institute for Advanced Immunochemical Studies, ShanghaiTech University, Shanghai, 201210, China.
| | - Jie Zhang
- Key Laboratory of Thermoregulation and Inflammation of Sichuan Higher Education Institutes, Chengdu Medical College, Chengdu, 610500, China.
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Tamada M, Ohi Y, Kodama D, Miyazawa K, Goto S, Haji A. Modulation of excitatory synaptic transmissions by TRPV1 in the spinal trigeminal subnucleus caudalis neurons of neuropathic pain rats. Eur J Pharmacol 2021; 913:174625. [PMID: 34758353 DOI: 10.1016/j.ejphar.2021.174625] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Revised: 10/29/2021] [Accepted: 11/04/2021] [Indexed: 01/16/2023]
Abstract
The present study examined contribution of the transient receptor potential vanilloid 1 channel (TRPV1) to the chronic orofacial pain. Bilateral partial nerve ligation (PNL) of the mental nerve, a branch of trigeminal nerve, was performed to induce neuropathic pain. The withdrawal threshold in response to mechanical stimulation of the lower lip skin was substantially reduced after the surgery in the PNL rats while it remained unchanged in the sham rats. This reduction in the PNL rats was alleviated by pregabalin injected intraperitoneally (10 mg/kg) and intracisternally (10, 30, 100 μg). Furthermore, an intracisternal injection of AMG9810, an antagonist of TRPV1, (1.5, 5.0 μg) attenuated the reduction of withdrawal threshold. Spontaneous and miniature excitatory postsynaptic currents (sEPSCs and mEPSCs) were recorded from the spinal trigeminal subnucleus caudalis (Vc) neurons in the brainstem slice, which receive the orofacial nociceptive signals. In the PNL rats, superfusion of capsaicin (0.03, 0.1 μM) enhanced their frequency without effect on the amplitude and the highest concentration (0.3 μM) increased both the frequency and amplitude. In the sham rats, only 0.3 μM capsaicin increased their frequency. Thus, capsaicin-induced facilitation of sEPSCs and mEPSCs in the PNL rats was significantly stronger than that in the sham rats. AMG9810 (0.1 μM) attenuated the capsaicin's effect. Capsaicin was ineffective on the trigeminal tract-evoked EPSCs in the PNL and sham rats. These results suggest that the chronic orofacial pain in the PNL model results from facilitation of the spontaneous excitatory synaptic transmission in the Vc region through TRPV1 at least partly.
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Affiliation(s)
- Mayo Tamada
- Laboratory of Neuropharmacology, School of Pharmacy, Aichi Gakuin University, 1-100 Kusumoto-cho, Chikusa-ku, Nagoya, 464-8650, Japan; Department of Orthodontics, School of Dentistry, Aichi Gakuin University, 1-100 Kusumoto-cho, Chikusa-ku, Nagoya, 464-8650, Japan.
| | - Yoshiaki Ohi
- Laboratory of Neuropharmacology, School of Pharmacy, Aichi Gakuin University, 1-100 Kusumoto-cho, Chikusa-ku, Nagoya, 464-8650, Japan.
| | - Daisuke Kodama
- Laboratory of Neuropharmacology, School of Pharmacy, Aichi Gakuin University, 1-100 Kusumoto-cho, Chikusa-ku, Nagoya, 464-8650, Japan.
| | - Ken Miyazawa
- Department of Orthodontics, School of Dentistry, Aichi Gakuin University, 1-100 Kusumoto-cho, Chikusa-ku, Nagoya, 464-8650, Japan.
| | - Shigemi Goto
- Department of Orthodontics, School of Dentistry, Aichi Gakuin University, 1-100 Kusumoto-cho, Chikusa-ku, Nagoya, 464-8650, Japan.
| | - Akira Haji
- Laboratory of Neuropharmacology, School of Pharmacy, Aichi Gakuin University, 1-100 Kusumoto-cho, Chikusa-ku, Nagoya, 464-8650, Japan.
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Asaoka R, Ohi Y, Miyazawa K, Goto S, Haji A. Involvement of presynaptic TRPV1 channels in prostaglandin E 2-induced facilitation of spontaneous synaptic transmission in the rat spinal trigeminal subnucleus caudalis. Brain Res 2019; 1715:115-125. [PMID: 30898677 DOI: 10.1016/j.brainres.2019.03.015] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Revised: 01/10/2019] [Accepted: 03/16/2019] [Indexed: 10/27/2022]
Abstract
Prostaglandin E2 (PGE2) synthesized in the central nervous system influences various physiological functions including nociception. Recently, we have demonstrated that PGE2 facilitates spontaneous synaptic transmission through presynaptic EP1 receptors in the spinal trigeminal subnucleus caudalis (Vc) neurons that receive nociceptive signals from the orofacial area. Increasing evidence suggests that the action of PGE2 is related to activation of transient receptor potential vanilloid 1 (TRPV1) channels. The present study investigated whether TRPV1 channels contribute to the facilitatory effect of PGE2 on synaptic transmission in the Vc neurons. Spontaneous excitatory and inhibitory postsynaptic currents (sEPSCs and sIPSCs) were recorded from Vc neurons in the rat brainstem slice by whole-cell patch-clamp mode. Superfusion of capsaicin (0.3, 1.0 μM) concentration-dependently increased the frequency of both sEPSCs and sIPSCs without any significant effect on their amplitude. The effect of capsaicin was completely abolished by a TRPV1 channel blocker AMG9810 (0.1 μM). PGE2 (5.0 μM) increased the frequency of sEPSCs and sIPSCs. This facilitatory effect of PGE2 was attenuated by AMG9810 and in neurons desensitized by repeated application of capsaicin. While a low concentration of either PGE2 (1.0 μM) or capsaicin (0.1 μM) had an insignificant effect on the sEPSCs and sIPSCs, co-application of these drugs increased their frequency. The present study demonstrated involvement of the presynaptic TRPV1 channels in PGE2-induced facilitation of spontaneous synaptic transmissions and suggests interaction of PGE2 with TRPV1 channels in modification of nociceptive signals from the orofacial area to the Vc neurons.
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Affiliation(s)
- Ryo Asaoka
- Laboratory of Neuropharmacology, School of Pharmacy, Aichi Gakuin University, Nagoya, Japan; Department of Orthodontics, School of Dentistry, Aichi Gakuin University, Nagoya, Japan
| | - Yoshiaki Ohi
- Laboratory of Neuropharmacology, School of Pharmacy, Aichi Gakuin University, Nagoya, Japan
| | - Ken Miyazawa
- Department of Orthodontics, School of Dentistry, Aichi Gakuin University, Nagoya, Japan
| | - Shigemi Goto
- Department of Orthodontics, School of Dentistry, Aichi Gakuin University, Nagoya, Japan
| | - Akira Haji
- Laboratory of Neuropharmacology, School of Pharmacy, Aichi Gakuin University, Nagoya, Japan.
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